Radio receiving set



Jun'ews, 1937. -V.NEEDHAM 31 RADIO RECEIVING SET Filed Dec. 16, 1935 2 Sheets-Shet l.

1 Needfiam Julie 8, 1937. v V 2,083,170

RADIO RECEIVING SET Filed Dec. '16, 1935 2 Sheets-Sheet 2 25 a; I a

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27 I I j 7 l/VSMLAT/OM Patented June 8, 1937 UNITED STATES PATENT QFFICE RADIO RECEIVING SET Virgil Needham, Osceola, Ark.

Application December 16, 1935, Serial No. 54,775

1 Claim.

This invention relates to an improved radio receiving set and seeks, among other objects, to provide a device of this character which may be utilized for receiving radio programs from broadcasting stations.

One object of the invention is to provide a radio receiving set which may be operated without the use of vacuum tubes, batteries, or house current, and which will render satisfactory service in the reception of programs.

Another object of the invention is to provide a radio receiving set which may be tuned with I ease and which may be readily carried from place to place.

A further object of the invention is to provide a device of this character which will comprise a minimum number of working parts and which may, therefore, be manufactured cheaply.

And a still further object of the invention is to provide a radio receiving set which will embody a wiring system of such nature that incoming signals will be strengthened.

Other and incidental objects of the invention not specifically mentioned in the foregoing will render themselves apparent during the course of the following description.

In the drawings:

Figure 1 is a perspective view of my radio receiving set.

Figure 2 is an enlarged vertical sectional view thereof.

Figure 3 is a bottom View of the set and showing particularly the tuning coil and inductance network employed.

Figure 4 is a diagrammatic View of the circuit arrangement employed.

Referring now to the drawings, wherein like numerals of reference designate like parts, the numeral I indicates a cabinet, or case, which is provided with a removable bottom wall 2, a vertical rear wall 3, a slanting front wall 4, and a relatively narrow top wall 5.

The case i may be made of a good grade of wood or, if desired, a rubber composition may be employed. The front wall or panel 4 is shown slanting upwardly but, if desired, this front wall may be mounted vertically. Mounted on the front wall, at spaced points, are handles 6 which permit ready carrying of the device from place to place. The front wall is provided with a slot which is relatively narrow and extends throughout the major portion of the length of said front wall. The purpose for the slot will be explained in detail hereinafter. End walls 8 and 9 close the opposite ends of the case and have their outer surfaces flush with the edges of the top wall and front and rear walls. 7

Mounted'within the case beneath the front wall 4 and in alinement with the slot I, is a coil form I0 which extends throughout the entire length of 5 the case and has its ends seated in the end walls 8 and 9. A tuning coil I2 is wound about the form I0 and the inductance of said coil is suitable for tuning to the broadcast frequencies.

Mounted on' the wall A in substantiallyoverl0 hanging. relationship to the slot 1 is a guide rod I3 which is bent at its ends and secured to the wall 4 by screws I4 at opposite ends of the case.

A binding clip I5 is also secured by one of the screws I4 near the wall 8. Slidable on the rod I3 15 is a tuning control knob or spool I6 which is adapted to carry a contact arm IT. The contact arm I1 is formed on the end of a spring I8, which spring is electrically connected to the rod I3 within the spool and is guided by said spool 20 to extend toward the slot 'I with the arm I! extending through said slot into selective engage- V ment with turns of the tuning coil I2. It should be understood, of course, that insulation on the turns of the coil is removed in the path of the 25 arm. The inductance of the coil I2 may be varied, obviously, by shifting the knob or spool I6 along the rod I3 so that the radio receivin set will be responsive to various frequencies to correspond to the frequencies of different broad- 30 casting stations. Mounted on the top wall 5 medially of its length and width is a detector I9 which is of the well known crystal type and is shown with a crystal therein and an adjustable cat's whisker 2I which is mounted on a shift- 35 able arm 22. Binding posts 23 are mounted on the detector and the detector is held in place by a screw 24.

Mounted on the end wall 8 are binding clips 25 and 26. Carried within the case and connected 40 at one end to the binding clip 26 is an inductance wire or coil 27 which is adapted to extend throughout the length of the case and is connected at its opposite end with the binding clip I5. Another inductance wire 28 is connected 5 with the clip 26 and is, in turn, connected \m'th an inductance wire 29 which extends throughout the major portion of the length of the case and this inductance wire is, in turn, connected with another inductance wire 30 which is con- 5 nected to a center tapped inductance wire 3|. An inductance wire 32 connects the center portion or tap of the wire 3I with a conductor 33 which is electrically connected with one end of the coil I2. An inductance wire 34- connects the 55 conductor 33 with the end of the inductance coil 2! remote from the binding clip 26. An inductance wire 35 is connected to the coil 21 near its remote end and an inductance wire 36 connects the conductor 33 with the wire 29 near one end thereof. An inductance wire 3! connects the wire 29 with a conductor 38 which is connected to inductance wires 39 and 40. The inductance wire 4!) is connected at its other end with a connector connecting the wires 28 and 29. The opposite end of the wire 39 is connected to an inductance wire 4| and to the corresponding end of an inductance wire 42. The other binding post 23 is connected to the binding clip 25. The binding clips 25 and 26 are adapted to receive the phone tips of a head phone. The binding clip I is adapted for receiving the ground clip while an additional clip is employed for securing the antenna connection. It has been found in practice that the Wires and conductors numbered 21 through 49 inclusive have increased the signal strength of incoming signals.

My improved radio receiving set is simple in construction and easy to operate. It may be readily carried from place to place and, inasmuch as it requires no batteries it will be cheap to use. The absence of batteries or electrical connections, it is believed, will reduce interference of a local nature.

A reading of the foregoing description Will disclose that I have provided a simple and highly efficient radio receiving set which may be manufactured cheaply.

Having thus described the invention, what I claim is:

Apparatus of the class described including a case, having front and rear walls, top and bottom walls and end walls, said front wall having a longitudinal slot, an inductance coil form extending beneath the slot and having its ends secured by said end walls, an inductance coil wound about said coil form, a rod over hanging the slot, a knob carried by the rod, a spring carried by the knob and electrically connected with the rod, a contact arm carried by the spring and extending through the slot into engagement with the inductance coil, said spring urging the contact arm toward said coil and said rod, the contact arm and spring cooperating with the coil for varying the inductance thereof, a crystal detector mounted on the top wall of the case, coils mounted within the case, clips mounted on an end wall of said case, a clip mounted on said rod, and circuit connections for the inductance coil, crystal detector and last mentioned coils, certain of said circuit connections being connected to the clips and said clips being adapted to receive the phone tips of a head phone and ground connections, and means carried on the opposite end wall to receive an antenna connection, said apparatus being adapted to receive radio broadcasting programs.

VIRGIL NEEDHAM. 

